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United States Patent |
5,030,731
|
Slongo
,   et al.
|
July 9, 1991
|
Coating material stabilized against the action of light
Abstract
Blocked benzotriazoles of the formula I or II
##STR1##
wherein x is 1 or 2, R.sup.1 in the case of x=1 and in the formula II is
an acyl group of the formula --CO--R.sup.5, a sulfonyl group of the
formula --SO.sub.2 --R.sup.6, a phosphoryl group of the formula
--P(O).sub.r (R.sup.14)(R.sup.15), and in the case of x=2 is --CO-- or a
diacyl group of the formula --CO--CO-- or --CO--R.sup.7 --CO--, and
R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.14 and
R.sup.15 have the meanings defined in claim 1, are crypto light
stabilizers which can be activated by short-wave irradiation. Their use in
coating materials is of interest in cases in which light stabilizers
containing the free OH compounds have disadvantages with regard to their
application.
Inventors:
|
Slongo; Mario (Tafers, CH);
Rembold; Manfred (Aesch, CH)
|
Assignee:
|
Ciba-Geigy Corporation (Ardsley, NY)
|
Appl. No.:
|
427919 |
Filed:
|
October 24, 1989 |
Foreign Application Priority Data
| Nov 01, 1984[CH] | 5220/84 |
| Feb 01, 1985[CH] | 453/85 |
Current U.S. Class: |
548/260; 548/261 |
Intern'l Class: |
C07D 249/16; C07D 403/00 |
Field of Search: |
548/261
|
References Cited
U.S. Patent Documents
3600397 | Aug., 1971 | Seki et al. | 524/91.
|
4247628 | Jan., 1981 | Uchida et al. | 430/551.
|
4775707 | Oct., 1988 | Slongo et al. | 524/91.
|
Primary Examiner: Morgan; Kriellion
Attorney, Agent or Firm: Hall; Luther A. R.
Parent Case Text
This application is a continuation of Ser. No. 215,104, filed on July 5,
1988, now abandoned, which is in turn a divisional of Ser. No. 065,655,
filed on June 22, 1987, now U.S. Pat. No. 4,775,707, issued on Oct. 4,
1988, which is in turn a continuation of Ser. No. 792,075, filed on Oct.
28, 1985, now abandoned.
Claims
What is claimed is:
1. A compound of the formula I or II
##STR24##
wherein x is 1, R.sup.1 is an acyl
group of the formula --CO--R.sup.5, a sulfonyl group of the
formula --SO.sub.2 --R.sup.6, a phosphoryl group of the formula
P(O).sub.r (R.sup.14) (R.sup.15),
R.sup.2 is C.sub.1 -C.sub.12 -alkyl, C.sub.5 -C.sub.12 -cycloalkyl, phenyl,
C.sub.7 -C.sub.9 -phenylalkyl, C.sub.3 -C.sub.5 -alkenyl or halogen,
R.sup.3 in the formula I is a group of the formula --(CH.sub.2).sub.n
--COOR.sup.9 or --(CH.sub.2).sub.n --CO--N(R.sup.10) (R.sup.11), and in
the formula II is a divalent group of the formula:
--(CH.sub.2).sub.n --CO--O--(CH.sub.2).sub.q --O--CO--(CH.sub.2).sub.n --,
--(CH.sub.2).sub.n --CO--O--(CH.sub.2 CH.sub.2 O).sub.p
--CO--(CH.sub.2).sub.n -,
--(CH.sub.2).sub.n --CO--NH--R.sup.12 --NH--CO--(CH.sub.2).sub.n --
or
##STR25##
R.sup.4 is hydrogen, halogen, C.sub.1 --C.sub.8 -alkyl, C.sub.7 --C.sub.9
-phenylalkyl,
C.sub.1 --C.sub.8 -alkoxy or C.sub.2 --C.sub.8 -alkoxycarbonyl,
R.sup.5 is C.sub.1 -C.sub.18 -alkyl, C.sub.2 -C.sub.18 -alkenyl, --CH.sub.2
CO--CH.sub.3, phenyl, phenyl substituted by C.sub.1 -C.sub.12 -alkyl,
C.sub.1 -C.sub.4 -alkoxy or benzoyl, or is C.sub.7 -C.sub.12 -arylalkyl or
C.sub.1 -C.sub.12 -alkoxy,
R.sup.6 is C.sub.1 -C.sub.12 -alkyl, C.sub.6 -C.sub.10 -aryl or C.sub.7
-C.sub.18 alkylaryl,
R.sup.9 is hydrogen, C.sub.1 -C.sub.12 -alkyl or a group of the formula
--(CH.sub.2 CH.sub.2 O).sub.p --R.sup.1,
R.sup.10 and R.sup.11 independently of one another are hydrogen, C.sub.1
-C.sub.12 -alkyl, which can be interrupted by O or N, C.sub.5 -C.sub.12
-cycloalkyl, C.sub.7 -C.sub.9 -phenylalkyl, C.sub.3 -C.sub.5 -alkenyl,
phenyl or a 2,2,6,6-tetramethyl-4-piperidinyl radical, or R.sup.10 and
R.sup.11 together are C.sub.4 -C.sub.6 -alkylene, -oxaalkylene or
-azaalkylene,
R.sup.12 is C.sub.1 -C.sub.12 -alkylene, which can be interrupted by 1-3 O
atoms,
R.sup.13 is C.sub.1 -C.sub.12 -alkyl or C.sub.6 -C.sub.10 -aryl,
R.sup.14 and R.sup.15 independently of one another are each C.sub.1
-C.sub.12 -alkoxy, phenoxy, C.sub.1 -C.sub.12 -alkyl, cyclohexyl, benzyl,
phenyl or tolyl,
n is 1 or 2, p is a number from 1 to 10, q is a number from: 2 to 12, and r
is 0 or 1.
2. A compound of the formula I according to claim 1, wherein x=1, R.sup.1
is a group of the formula --CO--R.sup.5 or --SO.sub.2 --R.sup.6, R.sup.2
is C.sub.1 -C.sub.12 -alkyl, cyclohexyl or C.sub.7 -C.sub.9 -phenylalkyl,
R.sup.3 is a group --CH.sub.2 CH.sub.2 COOR.sup.9, R.sup.4 is hydrogen,
methyl or chlorine, R.sup.5 is C.sub.1 -C.sub.12 -alkyl, C.sub.2 -C.sub.4
-alkenyl, phenyl, benzyl or naphthylmethyl, R.sup.6 is methyl, phenyl or
C.sub.7 -C.sub.15 -alkylphenyl, and R.sup.9 is C.sub.1 -C.sub.12 -alkyl.
3. A compound of the formula I according to claim 2, wherein x=1, R.sup.1
is a group --CO--R.sup.5 or --SO.sub.2 --R.sup.6, R.sup.2 is C.sub.1
-C.sub.8 -alkyl or .alpha.-dimethylbenzyl, R.sup.4 is hydrogen or
chlorine, and R.sup.3, and R.sup.5 and R.sup.6 have the meanings defined
in claim 12.
4. A compound of the formula II according to claim 1, wherein, R.sup.1 is a
group --CO--R.sup.5 or --SO.sub.2 --R.sup.6, R.sup.2 is C.sub.1 -C.sub.8
-alkyl or .alpha.-dimethylbenzyl, R.sup.3 is a group of the formula
--CH.sub.2 CH.sub.2 COO--(CH.sub.2).sub.q --OCOCH.sub.2 CH.sub.2 -- or
--CH.sub.2 CH.sub.2 CONH--R.sup.12 --NHCOCH.sub.2 CH.sub.2 --, R.sup.4 is
hydrogen or chlorine, R.sup.5 is C.sub.1 -C.sub.12 -alkyl, C.sub.2
-C.sub.4 -alkenyl, phenyl, benzyl or naphthylmethyl, R.sup.6 is methyl,
phenyl or C.sub.7 -C.sub.18 -alkylphenyl, R.sup.12 is C.sub.2 C.sub.8
-alkylene, and q is a number from 2 to 8.
Description
The invention relates to coating materials containing crypto light
stabilisers. Such compounds are activated by the action of short-wave
light in that they are converted photochemically into light stabilisers.
The compounds concerned are specific derivatives of
2-(2-hydroxyphenyl)-benzotriazoles having a blocked hydroxyl group.
Olson and Schroeter (J. Appl. Pol. Science 22 (1978), 2165-72) have already
suggested blocking the phenolic hydroxyl group of
2-(2-hydroxyphenyl)-benzotriazoles with chemical protective groups which
are subsequently removable, for example by hydrolysis, photolysis or
heating. These blocked benzotriazole derivatives do not absorb in the UV
range of 330-400 nm and as a result do not disturb the photopolymerisation
of UV-curable compositions. Because of their changed UV-absorption level
(their absorption maximum is about 290-310 nm), they are however not
suitable as light stabilisers, and have therefore to be converted after
photopolymerisation into the benzotriazoles having a free OH group, which
are known light stabilisers. The stated authors investigated the
possibility of blocking the OH group by silylation, by carbamoylation and,
in a later work (J. Appl. Pol. Science 28 (1983), 1159 -65), also by
etherification, esterification and sulfonylation. Various problems arise
in this connection, such as insufficient cleavage or discoloration
resulting from the formation of by-products. The O-sulfonylation and
photochemical cleavage are described as being the best methods. In the
case of this cleavage, there occurs essentially a photochemical Fries
rearrangement to the ortho-sulfonylphenols. This is possible because all
examined compounds are unsubstituted in the ortho-position (with respect
to the OH group).
It has now been found that with the use of
2-(2-hydroxyphenyl)-benzotriazoles, which are substituted both in the
para-position and in the ortho-position with respect to the OH group,
there are obtained, by blocking of the OH group, crypto light stabilisers
which have an absorption maximum likewise at 290-310 nm but which, in
spite of the substitution in the para-position and in the ortho-position,
can be photochemically reconverted into compounds having a free OH group.
They have a level of stability in darkness which is higher than that of
the compounds having an unsubstituted ortho-position. This factor is
important with respect to the commercial application, since lacquers are
frequently stored for long periods.
Compared with the known benzotriazole light stabilisers having a free OH
group, these crypto light stabilisers are of advantage when the coating
material is in contact with metals before or during application. All
2-(2-hydroxyphenyl)-benzotriazoles form with metal ions complexes which
are often coloured (for example in the case of Cu, Ni or Co), and they can
then cause a discoloration of the coating material. Another interesting
field of application for crypto light stabilisers is that covering
oxidatively drying coating materials which contain, as curing catalysts
(siccatives), organic metal compounds. In the presence of free
2-(2-hydroxyphenyl)-benzotriazoles, these metal compounds are bound by
coordination to the benzotriazole, and are then no longer effective as
curing catalysts.
The present invention thus relates to coating materials containing, as a
crypto light stabiliser, a compound of the formula I or II
##STR2##
wherein x iS 1 or 2, R.sup.1 in the case of x=1 and in the formula 11 is
an acyl group of the formula --CO--R.sup.5, a sulfonyl group of the
formula --SO.sub.2 --R.sup.6, a phosphoryl group of the formula
--P(O).sub.r (R.sup.14) (R.sup.15 of x=2 is --CO-- or a diacyl group of
the formula --CO--CO-- or --CO--R --CO--,
R.sup.2 is C.sub.1 -C.sub.12 -alkyl, C.sub.5 -C.sub.12 -cycloalkyl, phenyl,
C.sub.7 -C.sub.9 -phenylalkyl, C.sub.3 -C.sub.5 -alkenyl or halogen,
R.sup.3 in the formula I is C.sub.1 -C.sub.12 -alkyl, C.sub.5 -C.sub.12
-cycloalkyl, phenyl, C.sub.7 -C.sub.9 -phenylalkyl, halogen or a group of
the formula --(CH.sub.2).sub.n --COOR.sup.9 or --(CH.sub.2).sub.n
--CO--N(R.sup.10) (R.sup.11), and in the formula 11 is a divalent radical
of the formula:
--(CH.sub.2).sub.n --CO--O--(CH.sub.2).sub.q --O--CO--(CH.sub.2).sub.n --,
--(CH.sub.2).sub.n --CO--O--(CH.sub.2 CH.sub.2 O).sub.p
--CO--(CH.sub.2).sub.n --,
--(CH.sub.2).sub.n --CO--NH--R.sup.12 --NH--CO--(CH.sub.2).sub.n --
or
##STR3##
R.sup.4 is hydrogen, halogen, C.sub.1 -C.sub.8 -alkyl, C.sub.7 -C.sub.9
-phenylalkyl, C.sub.1 -C.sub.8 -alkoxy or C.sub.2 -C.sub.8
-alkoxycarbonyl,
R.sup.5 is C.sub.1 -C.sub.18 -alkenyl --CH.sub.2 --CO--CH.sub.3, phenyl,
phenyl substituted by C.sub.1 -C.sub.12 -alkyl, C.sub.1 -C.sub.4 -alkoxy
or benzoyl, C.sub.7 -C.sub.12 -arylalkyl or C.sub.1 -C.sub.12 -alkoxy,
R.sup.6 is C.sub.1 -C.sub.12 -alkyl, C.sub.6 -C.sub.10 -aryl or C.sub.7
-C.sub.18 -alkylaryl,
R.sup.7 is C.sub.1 -C.sub.10 -alkylene or phenylene,
R.sup.9 is hydrogen, C.sub.1 -C.sub.12 -alkyl or a group of the formula
--(CH .sub.2 CH.sub.2 O).sub.p --R.sup.1,
R.sup.10 and R.sup.11 independently of one another are hydrogen, C.sub.1
-C.sub.12 -alkyl, which can be interrupted by O or N, C.sub.5 -C.sub.12
-cycloalkyl, C.sub.7 -C.sub.9 -phenylalkyl, C.sub.3 -C.sub.5 -alkenyl,
phenyl or a 2,2,6,6-tetramethyl-4-piperidinyl radical, or R.sup.10 and
R.sup.11 together are C.sub.4 -C.sub.6 -alkylene, -oxaalkylene or
-azaalkylene,
R.sup.12 is C.sub.1 -C.sub.12 -alkylene, which can be interrupted by 1-3 O
atoms,
R.sup.13 is C.sub.1 -C.sub.12 -alkyl or C.sub.6 -C.sub.10 -aryl,
R.sup.14 and R.sup.15 independently of one another are each C.sub.1
-C.sub.12 -alkoxy, phenoxy, C.sub.1 -C.sub.12 -alkyl, cyclohexyl, benzyl,
phenyl or tolyl,
n is 1 or 2, p is a number from 1 to 10, q is a number from 2 to 12, and r
is 0 or 1.
As a monovalent acyl group R.sup.1 can be for example: acetyl, propionyl,
butyryl, valerianyl, capronyl (n-hexanoyl), 2-ethylhexanoyl, capryloyl
(n-octanoyl), caprionyl (n-decanoyl), lauroyl (n-dodecanoyl), palmityl
(n-hexadecanoyl), stearoyl (n-octadecanoyl), acryloyl, methacryloyl,
crotonyl, oleyl, linoleyl, benzoyl, 3-methylbenzoyl, 4-tert-butylbenzoyl,
4-hexylbenzoyl, 4-dodecylbenzoyl, 3- or 4-methoxy- or -ethoxybenzoyl,
4-benzoylbenzoyl, phenylacetyl, phenylpropionyl, naphthylacetyl,
methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, octyloxycarbonyl or
dodecyloxycarbonyl. Examples of R.sup.1 as a sulfonyl group are the
groups: methyl-, tert-butyl-, octyl-, dodecyl-, phenyl-, tolyl-,
naphthyl-, 4-nonylphenyl-, 4-dodecylphenyl- or mesitylenesulfonyl.
R.sup.1 as a diacyl group can be for example: oxalyl, succinyl, glutaroyl,
adipoyl, 2,2,4-trimethyladipoyl, sebacoyl (octamethylenedicarbonyl),
decamethylenedicarbonyl, terephthaloyl or isophthaloyl. R.sup.2, R.sup.3,
R.sup.4, R.sup.9, R.sup.10, R.sup.11, R.sup.13, R.sup.14, R.sup.15 as
alkyl can, within the given number of C atoms, be for example: methyl,
ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl,
pentyl, hexyl, heptyl, octyl, decyl or dodecyl.
R.sup.2 and R.sup.3 are preferably branched-chain alkyl groups.
R.sup.10 and R.sup.11 as alkyl interrupted by O or N can be for example:
2-butoxyethyl, 3-methoxypropyl, 3-ethoxypropyl, 3-isopropoxypropyl,
3-butylaminopropyl or 3-ethylaminopropyl.
R.sup.2, R.sup.10 and R.sup.11 as alkenyl can be for example: allyl,
methallyl or 2-butenyl.
R.sup.14 and R.sup.15 as alkoxy can be for example: methoxy, ethoxy,
isopropoxy, butoxy, hexyloxy, octyloxy, decyloxy or dodecyloxy.
R.sup.2 and R.sup.3 halogen can be for example: fluorine, chlorine or
bromine.
R.sup.2, R.sup.3, R.sup.10 and R.sup.11 as cycloalkyl can be for example:
cyclopentyl, cyclohexyl, methylcyclohexyl, cyclooctyl or cyclododecyl.
R.sup.2, R.sup.3, R.sup.10 and R.sup.11 as phenylalkyl can be for example:
benzyl, .alpha.-methylbenzyl, .alpha.-dimethylbenzyl or 2-phenylethyl.
R.sup.2 and R.sup.3 lalkyl are preferably .alpha.-dimethylbenzyl.
R.sup.4 as alkoxy or alkoxycarbonyl can be for example: methoxy, ethoxy,
isopropoxy, butoxy, hexyloxy, octyloxy, methoxycarbonyl, ethoxycarbonyl,
butoxycarbonyl or pentyloxycarbonyl. C.sub.1 -C.sub.4 -alkoxy or
alkoxycarbonyl radicals are preferred.
R.sup.7 as alkylene can be for example: methylene, 1,2-ethylene, tri-,
tetra-, penta-, hexa-, octa- or decamethylene.
When R.sup.10 and R.sup.11 together are alkylene, oxa- or azaalkylene, they
form together with the N atom to which they are bound a heterocyclic ring,
for example a pyrrolidine, piperidine, morpholine, piperazine or
hexamethylene ring.
R.sup.12 can be for example: 1,2-ethylene, tri-, tetra-, penta-, hexa-,
octa- or dodecamethylene, 2,4,4-trimethylhexamethylene,
3-oxaheptamethylene or 3,6-dioxadecamethylene.
Preferred compounds of the formula I are those wherein x=1, R.sup.1 is a
group of the formula --CO--R.sup.5,--SO.sub.2 --R.sup.6 or --P(O)
(R.sup.14) (R.sup.15), R.sup.2 is C.sub.1 -C.sub.12 --alkyl, cyclohexyl or
C.sub.7 -C.sub.9 -phenylalkyl, R.sup.3 is C.sub.1 -C.sub.12 -alkyl,
cyclohexyl, C.sub.7 -C.sub.9 -phenylalkyl or a group --CH.sub.2 CH.sub.2
COOR.sup.9, R.sup.4 is hydrogen, methyl or chlorine, R.sup.5 is C.sub.1
-C.sub.12 -alkyl, C.sub.2 -C.sub.4 -alkenyl, phenyl, benzyl or
naphthylmethyl, R.sup.6 is methyl, phenyl or C.sub.7 -C.sub.18
-alkylphenyl, R.sup.9 is C.sub.1 -C.sub.12 -alkyl, and R.sup.14 and
R.sup.15 independently, of one another are each C.sub.1 -C.sub.4 -alkoxy,
methyl or phenyl. Preferably, R.sup.1 therein is a group --CO-R.sup.5 or
--SO.sub.2 --R.sup.6, R.sup.2 is C.sub.1 -C.sub.8 -alkyl or
.alpha.-dimethylbenzyl, R.sup. 3 is C.sub.1 -C.sub.8 -alkyl,
.alpha.-dimethylbenzyl or a group --CH.sub.2 CH.sub.2 COOR.sup.9, and
R.sup.4 is hydrogen or chlorine.
Particularly preferred compounds of the formula I are those wherein x=1,
R.sup.1 is a group --CO--R.sup.5 or --SO.sub.2 --R.sup.6, R.sup.2 is
C.sub.1 -C.sub.8 -alkyl or .alpha.-dimethylbenzyl, R.sup.3 is C.sub.1
-C.sub.8 -alkyl, .alpha.-dimethylbenzyl or --CH.sub.2 CH.sub.2 COOR.sup.9,
R.sup.4 is hydrogen or chlorine, R.sup.5 is C.sub.1 -C.sub.12 -alkyl,
C.sub.2 -C.sub.4 -alkenyl, phenyl, benzyl or naphthylmethyl, R.sup.6 is
methyl, phenyl or C.sub.7 -C.sub.18 -alkylphenyl, and R.sup.9 is C.sub.1
-C.sub.12 -alkyl.
Preferred also are compounds of the formula I wherein x=2, R.sup.1 is a
group --CO--R.sup.7 --CO--, R.sup.2 is C.sub.1 -C.sub.8 -alkyl or
.alpha.-dimethylbenzyl, R.sup.3 is C.sub.1 -C.sub.8 -alkyl,
.alpha.-dimethylbenzyl or a group --CH.sub.2 CH.sub.2 COOR.sup.9, R.sup.4
is hydrogen or chlorine, R.sup.7 is C.sub.2 -C.sub.8 -alkylene, and
R.sup.9 is C.sub.1-C.sub.12 -alkyl.
Further preferred compounds are those of the formula II wherein R.sup.1 is
a group --CO--R.sup.5 or --SO.sub.2 --R.sup.6, R.sup.2 is C.sub.1 -C.sub.8
-alkyl or .alpha.-dimethylbenzyl, R.sup.3 is a group of the formula
--CH.sub.2 CH.sub.2 COO--(CH.sub.2).sub.q --OCOCH.sub.2 CH.sub.2 -- or
--CH.sub.2 CH.sub.2 CONH--R.sup.12 --NHCOCH.sub.2 CH.sub.2 --, R.sup.4 is
hydrogen or chlorine, R.sup.5 is C.sub.1 -C.sub.12 -alkyl, C.sub.2
-C.sub.4 -alkenyl, phenyl, benzyl or naphthylmethyl, R.sup.6 is methyl,
phenyl or C.sub.7 --C.sub.18 -alkylphenyl, R.sup.12 is C.sub.2 --C.sub.8
-alkylene, and q is a number from 2 to 8.
Some of these compounds are known and some are novel compounds. They can be
produced essentially from the corresponding hydroxyl compounds (R.sup.1
=H) by esterification of the hydroxyl group, using the customary methods
of acylation of phenolic OH groups, for example by reaction with
carboxylic acid anhydrides, carboxylic acid chlorides, sulfonic acid
chlorides or chlorophosphates. Examples of these are given in the
subsequent production examples. The hydroxyl compounds used as starting
materials are in part obtainable commercially, or can be produced by the
methods generally known for the production of
2-(2-hydroxyphenyl)-benzotriazoles.
Novel compounds are for example those compounds of the formula I wherein
R.sup.3 is a group --(CH.sub.2).sub.n --COOR.sup.9 or --(CH.sub.2).sub.n
--CON(R.sup.10) (R.sup.11); and also compounds of the formula II wherein
R.sup.3 is a divalent group of the formula
--(CH.sub.2).sub.n --CO--O--(CH.sub.2).sub.q --O--CO--(CH.sub.2).sub.n --,
--(CH.sub.2).sub.n --CO--O--(CH.sub.2 CH.sub.2 O).sub.p
--CO--(CH.sub.2).sub.n --,
--(CH.sub.2).sub.n --CO--NH--R.sup.10 --NH--CO--(CH.sub.2).sub.n --
or
##STR4##
Examples of individual compounds of the formula I are:
2-(2-acetoxy-3-methyl-5-tert-butyl-phenyl)-benzotriazole,
2-[2-acetoxy-3,5-di(tert-butyl)-phenyl]-benzotriazole,
2-(2-propionyloxy-3-isopropyl-5-tert-butyl-phenyl)-benzotriazole,
2-(2-butyroyloxy-3-sec-butyl-5-tert-butyl-phenyl)-benzotriazole,
2-[2-hexanoyloxy-3,5-di(tert-pentyl)-phenyl]-benzotriazole,
5-chloro-2-2-octanoyloxy-3,5-di(tert-butyl)-phenyl]benzotriazole,
5-methyl-2-(2-benzoyloxy-3,5-dimethyl-phenyl)-benzotriazole,
5-methoxy-2-[2-(4-chlorobenzoyloxy)-3,5-di(tert-butyl)phenyl-benzotriazole,
2-2-p-toluenesultonyloxy-3,5-di(tert-butyl)-phenyl]benzotriazole
2-2-dodecylsulfonyloxy-3,5-di(1,1.dimethylbenzyl)-phenyl]benzotriazole,
2-[2-(p-dodecylbenzenesulfonyloxy)-3-sec-butyl-5-tertbutylphenyl]-benzotria
zole,
di-[2-(benzotriazol-2-yl)-4,6-di(tert-butyl)-phenyl]adipate,
di-[2-(5-chlorobenzotriazol-2-yl)-4-methyl-6-tert-butylphenyl]-isophthalate
.beta.-[3-(benzotriazol-2-yl)-4-acetoxy-5-tert-butyl-phenyl]propionic acid
methyl ester,
[3-(benzotriazol-2-yl)-4-p-toluenesulfonyloxy-5-tert-butylphenyl]-acetic
acid butyl ester, and
-[3-(benzotriazol-2-yl)-4-benzoyloxy-5-cyclohexylphenyl]propionic
acid-2-butoxyethyl ester.
Examples of individual compounds of the formula II are:
di-[3-(benzotriazol-2-yl)-4-acetoxy-5-tert-butyl-phenylacetic acid ester]
of diethylene glycol,
di-[.beta.-(3-(benzotriazol-2-yl)-4-p-toluenesulfonyloxy-5-secbutyl-phenyl)
-propionic acid ester] of butanediol-1,4, and
N,N'-hexamethylene-bis[.beta.-(3-(benzotriazol-2-yl)-4butyroyloxy-5-methyl-
phenyl)-propionic acid amide].
The following Examples further illustrate the production of compounds such
as those listed above.
PRODUCTION EXAMPLES
Example A - Acetylation
100 ml of acetic anhydride are added to 1 mol of
5-chloro-2-[2-hydroxy-3,5-di(tert-butyl)-phenyl]-benzotriazole, and the
mixture is refluxed (140.degree. C.). After the addition of 0.6 g of
dimethylaminopyridine, the mixture is refluxed for a further 7 hours. A
specimen shows in the thin-layer chromatogram that no further starting
material is present. The excess acetic anhydride is distilled off in
vacuo, and the brown residue is dissolved in methylene chloride. The
solution is washed with a 5% Na.sub.2 CO.sub.3 solution and with water; it
is then dried over Na.sub.2 SO.sub.4 and concentrated by evaporation. The
crystalline residue is recrystallised from methanol to thus obtain
5-chloro-2-[2-acetoxy-3,5-di(tert-butyl)-phenyl]-benzotriazole in the form
of white crystals which melt at 132.degree.-134.degree. C. (compound No.
1).
There are obtained in an analogous manner the following acetoxy compounds
of the general formula
##STR5##
__________________________________________________________________________
Compound
No. R.sup.2 R.sup.3 R.sup.4
Physical constants
__________________________________________________________________________
2 tert.-butyl
--CH.sub.2 CH.sub.2 COOCH.sub.3
H m.p. 67-69.degree. (from ligroin)
3 tert.-butyl
--CH.sub.2 CH.sub.2 COOC.sub.8 H.sub.17
Cl
oil
(mixture of n- and iso-octyl)
C cal.
65.8%
found
66.1%
H cal.
7.4%
found
7.2%
N cal.
7.9%
found
8.1%
4 tert.-butyl
--CH.sub.2 CH.sub.2 COOCH.sub.2 CH.sub.2 OC.sub.2 H.sub.5
H viscous resin
C cal.
63.4%
found
63.4%
H cal.
6.5%
found
6.5%
N cal.
8.2%
found
8.2%
5 tert.-butyl
tert.-butyl H m.p. 155-157.degree. (from
ligroin)
6 tert.-pentyl
tert.-pentyl H m.p. 121-122.degree. (from
ligroin)
(1,1-dimethylpropyl)
7 sec.-butyl
tert.-butyl H viscous resin
C cal.
72.3%
found
72.3%
H cal.
7.4%
found
7.4%
N cal.
11.5%
found
11.5%
8 .alpha.-dimethylbenzyl
.alpha. -dimethylbenzyl
H m.p. 180-182.degree. (from
toluene)
9 tert.-butyl
--CH.sub.2 CH.sub.2 CONH(CH.sub.2).sub.6 NHCOCH.sub.2
CH.sub.2 -- H m.p. 87-90.degree. C.
10 tert.-butyl
--CH.sub.2 CH.sub.2 COOH
H m.p. 134-136.degree. C.
__________________________________________________________________________
Example B - Tosylation
0.1 mol of 2-(2-hydroxy-3-sec-butyl-5-tert-butyl-phenyl)benzotriazole is
dissolved in 200 ml of toluene. There is then added, with stirring, a
solution of 20 g of NaOH in 20 g of water and 0.01 mol of
tetrabutylammonium hydrogen sulfate (as phase-transfer catalyst), in the
course of which the organic phase assumes an intense yellowish-orange
colour. A solution of 0.11 mol of p-toluenesulfonyl chloride in 50 ml of
toluene is then slowly added dropwise at room temperature. The exothermic
reaction is compensated for by cooling with ice-water. The mixture is
subsequently stirred for 3 hours at room temperature, during which time
the colour of the toluene solution gradually disappears. A specimen
indicates in the thin-layer chromatogram that no further starting material
is present. The reaction mixture is poured into 1 litre of ice-water; the
organic phase is separated, washed twice with 300 ml of water each time
and dried over Na.sub.2 SO.sub.4. The solution is concentrated in vacuo,
and the residue is crystallised from ethanol to thus obtain 2-(2
-toluenesulfonyloxy-3-sec-butyl-5-tert-butylphenyl)-benzotriazole in the
form of white crystals which melt at 139.degree.-141.degree. C. (compound
No. 11).
There are obtained in an analogous manner the following sulfonates of the
general formula
##STR6##
__________________________________________________________________________
Compound
No. R.sup.2 R.sup.3 R.sup.4
R.sup.6
Physical constants
__________________________________________________________________________
12 tert.-butyl
tert.-butyl
H p-tolyl
m.p. 187-189.degree. (from ethanol)
13 tert.-pentyl
tert.-pentyl
H p-tolyl
m.p. 152-154.degree. (from ethanol)
14 .alpha.-dimethylbenzyl
.alpha.-dimethylbenzyl
H p-tolyl
m.p. 152-154.degree. (from
isopropanol)
15 tert.-butyl
--CH.sub.2 CH.sub.2 COOCH.sub.3
H p-tolyl
m.p. 123-125.degree. (from methanol)
16 tert.-butyl
--CH.sub.2 CH.sub.2 COOC.sub.8 H.sub.17
Cl C cal.
63.8%
found
64.1%
(mixture of n- and iso-
H cal.
6.6%
found
6.6%
octyl) N cal.
6.6%
found
6.8%
Cl
cal.
5.5%
found
5.5%
S cal.
5.0%
found
4.9%
17 tert.-pentyl
tert.-pentyl
H p-dodecyl-
C cal.
72.8%
found
72.7%
phenyl
H cal.
8.7%
found
8.7%
N cal.
6.4%
found
6.5%
18 tert.-butyl
tert.-butyl
H p-dodecyl-
C cal.
72.3%
found
72.0%
phenyl
H cal.
8.5%
found
8.5%
N cal.
6.7%
found
6.8%
19 tert.-butyl
tert.-butyl
H methyl
m.p. 149-151.degree.
20 tert.-pentyl
tert.-pentyl
H methyl
m.p. 88-90
21 tert.-butyl
--CH.sub.2 CH.sub.2 COOCH.sub.3
H methyl
m.p. 142-144.degree.
22 .alpha.-dimethylbenzyl
.alpha.-dimethylbenzyl
H methyl
m.p. 176-178.degree.
23 sec.-butyl
tert.-butyl
H p-tolyl
m.p. 139-141.degree. C.
__________________________________________________________________________
The bis-tosylate of the following formula is produced in an analogous
manner:
##STR7##
Example C - Esterification with acid chloride
0.12 mol of triethylamine is added to a solution of 0.08 mol of
2-[2-hydroxy-3,5-di(tert-butyl)-phenyl]-benzotriazole in 150 ml of
methylene chloride. To this solution is slowly added dropwise at
10.degree.-15.degree. C., with stirring, a solution of 0.08 mol of
2-naphthylacetyl chloride in 50 ml of methylene chloride. The temperature
is then allowed to rise to 20.degree.-25.degree. C., and the mixture is
stirred for 6 hours at this temperature. The triethylammonium chloride
which has precipitated is filtered off, and the filtrate is washed with
water, dried over Na.sub.2 SO.sub.4 and concentrated by evaporation. The
crystalline, reddish-coloured residue is recrystallised from hexane to
thus obtain
2-[2-(1-naphthylacetoxy)-3,5-di(tert-butyl)-phenyl]-benzotriazole in the
form of white crystals which melt at 150.degree.-151.degree. C. (compound
No. 25).
There are obtained in an analogous manner the following phenol esters of
the general formula
##STR8##
__________________________________________________________________________
Compound
No. R.sup.1 R.sup.2
R.sup.3 Physical constants
__________________________________________________________________________
26
sec.-butyl
tert.-butyl
m.p. 126-128.degree.
27
##STR9## tert.-butyl
tert.-butyl
m.p. 178-180.degree.
28
##STR10## tert.-pentyl
tert.-pentyl
m.p. 74-76.degree.
29
##STR11## tert.-butyl
tert.-butyl
m.p. 114-116.degree.
30
##STR12## tert.-butyl
tert.-butyl
m.p. 106-108.degree.
31 COCOOC.sub.2 H.sub. 5
tert.-butyl
(CH.sub.2).sub.2 COOCH.sub.3
m.p. 82-84.degree.
32 COCOOC.sub.2 H.sub.5
tert.-butyl
tert.-butyl
m.p. 112-114.degree.
33 COCOOC.sub.2 H.sub.5
tert.-pentyl
tert.-pentyl
m.p. 81-83.degree.
34 COCOOC.sub.2 H.sub.5
.alpha.-dimethyl-
.alpha.-dimethylbenzyl
m.p. 106-108.degree.
benzyl
35 COCHCH.sub.2 tert.-butyl
tert.butyl m.p. 104-106.degree.
36 COCHCH.sub.2 tert.-pentyl
tert.-pentyl
m.p. 101-103.degree.
37 COCHCH.sub.2 .alpha.-dimethyl-
.alpha.-dimethylbenzyl
m.p. 128-130.degree.
benzyl
38 COCHCH.sub.2 tert.-butyl
CH.sub.2 CH.sub.2 COOCH.sub.3
m.p. 84-86.degree.
__________________________________________________________________________
Example D - Esterification with acid chlorides by phase-transfer catalysis
0 1 mol of 2-[2-hydroxy-3,5-di(tert-butyl)-phenyl]-benzotriazole is
dissolved in 150-200 ml of toluene. To the solution are added 20 g of NaOH
dissolved in 20 ml of water (50% NaOH solution) and 0.01 mol of
tetrabutylammonium hydrogen sulfate (PTC). There is immediately formed an
orange-coloured emulsion, and this is heated to 40.degree. C. At this
temperature is slowly added dropwise a solution of 0.11 mol of
chloroformic acid butyl ester in about 30 ml of toluene. The reaction
proceeds exothermically, and from 45.degree.-50.degree. C. it is cooled
with ice-water. At the end of the dropwise addition, the reaction solution
has become light-yellow. Stirring is maintained for a further 2 hours,
after which time no further starting product can be identified in the
thin-layer chromatogram. The reaction solution is cooled to room
temperature, and about 200 ml of water are added. The organic phase is
then separated and is washed twice with 100 ml of water each time. The
toluene solution is dried with sodium sulfate and is afterwards
concentrated in a rotary evaporator. The light-yellow residue is
recrystallised from ethanol to thus obtain
2-[2-(butoxycarbonyloxy)-3,5-di(tert-butyl)-phenyl]-benzotriazole
(compound No. 39) in the form of white crystals which melt at
116.degree.-118.degree. C.
By variation of the acid chloride, there are obtained in an analogous
manner the following phenolic esters:
##STR13##
__________________________________________________________________________
Compound
No. R.sup.1 R.sup.2 R.sup.3 Physical
__________________________________________________________________________
constants
40 COOC.sub.4 H.sub.9 tert.-pentyl
tert.-pentyl
C cal. 71.0% found
70.9%
H cal. 8.4% found 8.3%
N cal. 9.5% found 9.3%
41 COOC.sub.4 H.sub.9 .alpha.-dimethylbenzyl
.alpha.-dimethylbenzyl
C cal. 76.7% found
76.9%
H cal. 6.8% found 6.7%
N cal. 7.6% found 7.7%
42 COOC.sub.4 H.sub.9 tert.-butyl
CH.sub.2 CH.sub.2 COOCH.sub.3
C cal. 66.2% found
66.2%
H cal. 7.0% found 6.9%
N cal. 9.5% found 9.7%
43 CO(CH.sub.2).sub.10 CH.sub.3
tert.-pentyl
tert.-pentyl
m.p. 51-54.degree.
44 CO(CH.sub.2).sub.10 CH.sub.3
.alpha.-dimethylbenzyl
.alpha.-dimethylbenzyl
C cal. 80.0% found
80.1%
H cal. 8.1% found 8.2%
N cal. 6.6% found 6.7%
45 CO(CH.sub.2).sub.6 CH.sub.3
tert.-butyl
tert.-butyl
C cal. 74.7% found
74.9%
H cal. 8.7% found 8.7%
N cal. 9.3% found 9.3%
46 CO(CH.sub.2).sub.6 CH.sub.3
tert.-pentyl
tert.-pentyl
C cal. 75.4% found
75.4%
H cal. 9.0% found 9.0%
N cal. 8.8% found 8.8%
47 CO(CH.sub.2).sub.6 CH.sub.3
.alpha.-dimethylbenzyl
.alpha.-dimethylbenzyl
C cal. 79.5% found
79.5%
H cal. 7.5% found 7.6%
N cal. 7.3% found 7.4%
48 CO(CH.sub.2).sub.6 CH.sub.3
tert.-butyl
CH.sub.2 CH.sub.2 COOCH.sub.3
C cal. 70.1% found
70.2%
H cal. 7.7% found 7.7%
N cal. 8.7% found 8.8%
49 PO(OC.sub.2 H.sub.5).sub.2
tert.-butyl
tert.-butyl
m.p. 118-120.degree.
50 PO(OC.sub.2 H.sub.5).sub.2
tert.-pentyl
tert.-pentyl
m.p. 93-95.degree.
51 PO(OC.sub.2 H.sub.5).sub.2
.alpha.-dimethylbenzyl
.alpha.-dimethylbenzyl
m.p. 124-126.degree.
52
tert.-butyl
tert.-butyl
m.p. 154-156.degree.
53
##STR14## tert.-pentyl
tert.-pentyl
m.p. 118-120.degree.
54
##STR15## .alpha.-dimethylbenzyl
.alpha.-dimethylbenzyl
m.p. 143-145.degree.
55
##STR16## tert.-butyl
CH.sub.2 CH.sub.2 COOCH.sub.3
m.p. 122-124.degree.
56
##STR17## tert.-butyl
tert.-butyl
m.p. 159-161.degree.
57
##STR18## tert.-pentyl
tert.-pentyl
m.p. 82-85.degree.
58
##STR19## .alpha. -dimethylbenzyl
.alpha.-dimethylbenzyl
m.p. 172-174.degree.
59
##STR20## tert.-butyl
CH.sub.2 CH.sub.2 COOCH.sub.3
C cal. 72.7% found
72.3% H cal. 5.5% found
5.6% N cal. 7.4% found
7.6%
60
##STR21## tert.-butyl
tert.-butyl
m.p. 137-138.degree.
__________________________________________________________________________
__________________________________________________________________________
##STR22##
Compound No.
R.sup.2 R.sup.3 Physical constants
__________________________________________________________________________
61 tert.-butyl
tert.-butyl
m.p. 180-182.degree.
62 tert.-pentyl
tert.-pentyl
m.p. 109-111.degree.
63 .alpha.-dimethylbenzyl
.alpha.-dimethylbenzyl
m.p. 201-204.degree.
64 tert.-butyl
CH.sub.2 CH.sub.2 COOCH.sub.3
m.p. 123-125.degree.
__________________________________________________________________________
The coating materials according to the invention can be pigmented or
unpigmented. They contain as the main component a binder which is
initially a soluble resin and which, after application, is converted into
an insoluble state. Curing can be effected either by heating or by a
chemical reaction. Examples of such binders are: alkyl resins, acrylic
resins, epoxide resins, melamine resins, urea resins, polyurethanes,
polyesters or phenolic resins, and mixtures thereof with one another..
The coating material is usually applied as a solution. Coating materials
with a small amount of solvent (high solids) or without solvent (with the
addition of reactive diluents) have recently become of increasing
importance in coating practice. In all cases, the addition of a light
stabiliser can be of interest. Examples in this respect are surface
lacquers for multilayer coatings, which lacquers are intended to protect
the pigmented lower layer against damage by light. Surface coatings of
this type are used in particular in vehicle construction. Further examples
are UV protective lacquers for furniture or for plastic films or sheets.
The present invention is of special importance with regard to coating
materials which on application come into contact with copper or with
copper alloys.
Depending on the purpose of their application, the coating materials can
contain, besides pigments and solvents, other additives, for example
flow-control agents, thixotropic agents, wetting agents, metal
deactivators or antioxidants. They can also contain, in addition to the
crypto light stabiliser according to the invention, a further light
stabiliser from the class of sterically hindered amines, since these
likewise do not absorb in the UV range of 330-400 nm.
The coating materials according to the invention can be applied to any
desired substrates, for example to metal, glass, ceramic, wood, paper or
plastic surfaces. The application is effected by the customary methods for
coating materials, for example by brushing, immersion or spraying, or by
electrostatic processes. The degree of activation of the light stabiliser
is governed by the extent to which short-wave light acts on the coating.
With a low level of irradiation, there will therefore occur a slow
activation, whereas intensive irradiation will result in a rapid
activation. The light stabiliser can also be artificially activated by
exposing the coating before its application to UV light. This can be
carried out before or after the curing of the coating. The manner in which
curing is effected will depend on the nature of the employed binder, for
example by heating or by oxidative curing.
The following Examples illustrate the application according to the
invention of crypto light stabilisers. Except where otherwise stated, the
symbol % denotes per cent by weight.
EXAMPLE 1:
Stabilisation of a two-layer metallic-effect lacquer
Aluminium sheets 0.5 mm in thickness are coated with an aluminium-pigmented
base lacquer based on polyester/ cellulose acetobutyrate/melamine resin.
There is then sprayed onto the wet base lacquer a clear lacquer of the
following composition:
58.3 parts of Viacryl .RTM. VC 373 (acrylic resin, Vianova, Vienna),
27.3 parts of Maprenal .RTM. MF 590 (melamine resin, Hochst AG, Frankfurt),
1.0 part of a 1% solution of a silicone oil in xylene,
4.0 part of Solvesso .RTM. 150 (aromatic solvent mixture),
5.4 parts of xylene, and
Also added is 0.9 part of the crypto light stabiliser given in Table 1,
corresponding to 2% relative to the binder. The viscosity of this clear
lacquer is adJusted to 21 sec/DIN cup 4. It is applied in a dry-layer
thickness of 40 .mu.m, and is stoved at 130.degree. C. for 30 minutes.
The specimens are in the one case weathered in a QUV rapid weatherometer
(Fa. Q-Panel) and in the other case in a Xenotest .RTM. 1200 (Fa. Heraeus)
up to 5200 hours. After 800 hours in each case, the 20.degree. gloss
according to DIN 67530 is measured, and the surface of the specimens is
examined for cracking under the stereomicroscope. As a basis of
comparison, there is used a) an unstabilised specimen, and b) a
non-blocked UV absorber of the formula
##STR23##
The results are summarised in Tables 1 and 2.
TABLE 1
______________________________________
QUV - 2 - Weathering
Cracking
Light 20.degree. gloss after
noticeable
stabiliser 0 1600 3200 4800 h
after
______________________________________
none 91 42 -- -- 2800 h
compound No. 2
91 79 76 26 5200 h
comparison A
90 81 69 29 5200 h
______________________________________
TABLE 2
______________________________________
Xenotest .RTM. 1200 - Weathering
Cracking
Light 20.degree. gloss after
noticeable
stabiliser 0 1600 3200 4800 h
after
______________________________________
without 91 38 31 -- 3600 h
compound No. 2
91 68 54 31 5200 h
comparison A
90 61 44 28 5200 h
______________________________________
As can be seen from the Tables, the protective action of the crypto light
stabiliser is approximately equal to that of the non-blocked light
stabiliser.
EXAMPLE 2
Discoloration as a result of contact with copper
The clear lacquer described in Example 1 is brought into contact, before
its application, for 48 hours with a copper sheet. The lacquer is then
applied in a layer thickness of 40 .mu.m to sheets which have been primed
with a TiO.sub.2 -pigmented white lacquer based on polyester resin. The
specimens are subsequently stoved for 30 minutes at 130.degree. C.
The discoloration of the specimens is measured in the one case according to
the Yellowness Index (YI) and in the other case according to DIN 6174 (as
.DELTA.E).
There is used as a comparison the commercial UV absorber
2-[2-hydroxy-3,5-di-(1,1-dimethylbenzyl)-phenyl]-benzotriazole =comparison
B.
The results are summarised in Table 3.
TABLE 3
______________________________________
Light stabiliser YI .DELTA.E
______________________________________
none 3.4 2.1
1% of compound No. 2
3.1 2.0
1% of comparison B 5.8 3.2
______________________________________
It is seen from the Table that the free hydroxyphenylbenzotriazole causes a
yellowing, whereas the crypto light stabiliser does not.
EXAMPLE 3
Storage stability of the crypto light stabilisers
Methanol solutions 5.10.sup.-5 mol/l of a benzotriazole derivative are
stored for 14 days in darkness. The UV spectrum of the solutions is
measured before and after storage. The solutions of the compounds Nos. 2,
5, 6, 7, 8, 11, 12, 13, 14, 15, 17 and 18 exhibit no alteration of the
spectrum.
Similar blocked benzotriazole derivatives, which are unsubstituted in the
ortho-position with respect to the blocked OH group, exhibit after storage
an alteration of the spectrum, which indicates that a partial unblocking
has occurred during storage in darkness.
EXAMPLE 4
A two-component stoving lacquer based on acrylic resin is prepared from the
following components
Portion A
______________________________________
72.8 g of an amine-functional acrylic resin
(Setalux .RTM. 83-03 BX 55, Fa. Synthese, Netherlands),
0.9 g of a flow-control agent based on silicone oil
(Baysilon .RTM. oil, Fa. Bayer AG), and
9.0 g of xylene
82.7 g
______________________________________
Portion B
17.3 g of an epoxy-functional acrylic resin (Setalux .RTM. 83-04 5 70, Fa.
Synthese, NL).
The portions A and B are combined, and a solution of the light stabiliser
given in Table 4 in xylene is added. This lacquer is sprayed onto a metal
sheet which is primed with a silver-metallic stoving lacquer based on
polyester/ cellulose acetobutyrate/melamine resin. After exposure to the
air at room temperature for one hour, the specimens are stoved for 30
minutes at 135.degree. C. The layer thickness of the surface lacquer is
about 40 .mu.m.
The discoloration occurring on stoving is measured according to DIN 6174 as
shade difference .DELTA.E.
There are compared in each case the free hydroxybenzotriazoles and the
0-acyl compounds thereof.
TABLE 4
______________________________________
Light stabiliser .DELTA.E
______________________________________
none 0.7
2% of compound No. 8
1.0
2% of comparison B 12.8
2% of compound No. 6
0.7
2% of comparison C 4.4
______________________________________
comparison B=2-[2-hydroxy-3,5-di(1,1-dimethylbenzyl)phenyl]-benzotriazole
comparison C=2-[2-hydroxy-3,5-di(tert-pentyl)-phenyl]benzotriazole.
EXAMPLE 5
Discoloration on weathering
The clear lacquer described in Example 1 is applied in a dry-film thickness
of 40 .mu.m to metal sheet primed white. The specimens are stoved at
130.degree. C for 30 minutes and then weathered in a Florida apparatus for
3 months. The degree of whiteness according to DIN 6174 is measured before
and after weathering, and from the result is determined in each case the
shade difference .DELTA.E. The results are summarised in Table 5.
TABLE 5
______________________________________
Light stabiliser .DELTA.E
______________________________________
none 3.2
2% of compound No. 6
1.0
2% of compound No. 13
0.8
2% of compound No. 20
0.6
2% of compound No. 46
1.0
2% of compound No. 62
1.2
______________________________________
EXAMPLE 6
Combination with a catalyst which can be cleaved by UV
A acid-curable acrylic resin/melamine resin clear lacquer is prepared from:
57.3 parts of Acryloid .RTM. AT 410 (acrylic resin, Rohm and Haas Corp.,
USA) (75% solids content),
18.0 parts of Cymel .RTM. 301 (melamine resin, Amer. Cyanamid),
10.0 parts of butylacetate,
1.8 parts of celluose acetobutyrate CAB 551 (Eastman Chem. Corp.),
2.6 parts of a flow-control agent (Modaflow .RTM., Monsanto Corp.) and
10.5 parts of butanol.
The solids content of the lacquer is 65%. The lacquer is knife-coated in a
dry-film thickness of 40 .mu.m onto glass plates. The specimens are
irradiated for 10 seconds with a 160 W UV-lamp, and then stoved at
120.degree. C for 30 minutes. There is used as a curing catalyst that can
be activated by UV light 1% of benzoin-p-toluenesulfonate, which cleaves
off p-toluenesulfonic acid on exposure to UV light. A blocked acid
catalyst of this type has the advantage that it effects no curing in
darkness. It has the disadvantage that in the presence of UV-absorber
light stabilisers the curing of the lacquer is incomplete. When however
there is used as light stabilisers the 0-acylated benzotriazoles according
to the invention, the activity of the curing catalyst is not hindered, as
is shown by the following Table 6. The curing of the lacquer is assessed
in these tests by measurement of the pendulum hardness according to DIN
53157. The specimens are subsequently weathered in the Xenon
Weatherometer, and the percentage gloss retention is thus determined.
TABLE 6
______________________________________
Gloss retention in %
Pendulum
after weathering of
hardness
Light stabiliser
1000 h 2000 h 3000 h
(sec)
______________________________________
none 83 5 -- 204
1% of comparison C*
91 82 4 78
1% of compound No. 2
70 56 2 154
1% of compound No. 5
75 77 6 155
1% of compound No. 5
102 63 23 122
+1% of HALS**
1% of compound No. 6
98 78 5 158
______________________________________
*comparison C = 2[2hydroxy-3,5-di-tert-pentyl-phenylbenzotriazole (Tinuvi
.RTM. 328)
**HALS =
8acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triaza-spiro[4,5]decanedione2
4 (Tinuvin .RTM. 440)
It is seen from the above that the free benzotriazole (comparison C) does
provide good protection against light but greatly reduces the curing of
the lacquer. With the light stabilisers according to the invention there
is however obtained both a good protection against light and satisfactory
curing. The level of protection against light can be increased by the
addition of a light stabiliser of the sterically hindered amine type
(HALS).
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